Separating device

Abstract

Use of a device (1) for separating different solid fractions of a solid mixture as feed material (2) in a mechanical separation process with at least two screw shafts (3), wherein the screw shaft (3) has a core tube (4) and a helix (5) with a plurality of turns (6), in particular spirally extending around the core tube (4), wherein adjacent turns (6) are spaced apart from each other by a turn spacing (7), wherein the conveying direction (X) of the screw shaft (3) is at least substantially parallel to the axis of rotation (8) of the screw shaft (3), wherein the screw shafts (3) are arranged such that they form a screen deck which is used for classifying solid and lumpy feed material (2), wherein the helixes (5) of immediately adjacent screw shafts (3) interlock, wherein the device (1) is designed such thatthat a separation into at least three fractions takes place and that a separation into at least two fractions takes place above the screw shafts (3), characterized in that the pitch (7) of at least one screw shaft (3) increases at least partially in the conveying direction (X).

Description

[0001] The invention relates to a use of a device for separating feed material with at least two screw shafts according to the preamble of claim 1.

[0002] The invention relates in particular to the technical field of sorting and / or classifying feed material, especially in the field of waste separation. A clean and sufficiently precise separation of the feed material into different fractions makes it possible to directly utilize different fractions of the feed material or to subject them to different post-treatment processes or stages. For example, large and / or elongated pieces can be separated from smaller particles or components of the feed material.

[0003] In the context of the invention, the term “separation” includes both classifying and sorting. Classifying is understood to be a mechanical separation process for solid mixtures, whereby different geometric characteristics, for example size, are utilized for the separation process. This can result in a division into coarse and fine material, among other things. Sorting in this context is understood to be a mechanical separation process in which a solid mixture with different material characteristics is divided into fractions with the same material characteristics. Suitable factors for sorting are, for example, the density, color, shape, wettability or magnetizability of the feed material. Accordingly, the term separation in the present invention includes a division of the feed material so that it can be divided into different fractions. This separation orSeparation is used to process recycled material or to classify at least substantially solid material.

[0004] EP 1 570 919 B1 discloses a device for sorting essentially solid material, wherein in the known device so-called spiral rollers or screw shafts rotate as rotating elements about their longitudinal axes. The spiral rollers are arranged parallel to one another in approximately the same plane. Furthermore, the spiral rollers are only mounted on one side, mesh with one another, and have the same direction of rotation. In the known device, the feed material is fed at least essentially transversely to the longitudinal axis or axial direction of the spiral rollers or specifically in the axial direction of the spiral rollers. The known device is designed to separate the materials to be sorted into two fractions above the spiral rollers, namely a long part fraction and a fraction of cubic parts above the spiral rollers.A third fraction can be separated below the spiral rollers, which can include, for example, the fines of the feed material. At least one fraction above the spiral rollers can be discharged via the open side perpendicular to the longitudinal axis of the spiral rollers, since they are only held on one side.

[0005] A disadvantage of the separating device known from EP 1 570 919 B1 is that feed material consisting of lumpy, hard material, in particular stones, pebbles, rubble, and / or metal parts such as screw nuts, especially with an at least substantially cubic structure, can become jammed between the spiral rollers. Such jamming of feed material can result in severe, localized overload events. Such an overload event can cause severe machine damage, which can lead to a prolonged downtime. Ultimately, the connecting elements of the drive device connecting the screw shafts to one another, in particular gear roller chains, can become loose, break off, or even tear due to the overload event.

[0006] In addition, an overload event results in a high level of noise, accompanied by a loud grinding sound and other, particularly high-frequency, noises. Such shrill noises are often due to wear processes.

[0007] Furthermore, the separation result is usually unsatisfactory in the case of highly branched feed material and / or feed material with an increased layer height and separation into different fractions cannot be sufficiently guaranteed.

[0008] DE 10 2017 011 797 B3 relates to a device for separating feed material with at least two rotating elements, wherein the rotating elements are connected to one another via at least one connecting means of a drive device, so that at least two immediately adjacent rotating elements have a rotational direction coupling.

[0009] EP 0 562 692 A1 discloses a separating device with a plurality of rotating elements.

[0010] The object of the present invention is to avoid the disadvantages of the prior art or at least to reduce them substantially.

[0011] The aforementioned object is achieved according to the invention, at least essentially, when using a separation device of the type mentioned above in that the pitch of the windings of at least one screw shaft increases at least in some areas in the conveying direction. Preferably, the pitch of the windings increases at least in some areas for all screw shafts, in particular those arranged in parallel and / or meshing with one another, in the conveying direction.

[0012] According to the invention, a regional increase in the winding pitch is to be understood as meaning that the length of at least two immediately consecutive winding pitches increases in the conveying direction. Preferably, the length of at least three, more preferably at least four, consecutive winding pitches increases in the conveying direction.

[0013] The conveying direction is understood to be the direction that runs at least substantially parallel to the longitudinal extent of the core tube and parallel to the axis of rotation of the screw shaft. The device according to the invention can also have a further conveying direction, which can be orthogonal and / or transverse to the axes of rotation of the screw shafts. The distance between two consecutive turns of the helix characterizes the pitch of the helix, in particular the spiral-shaped helix, wherein the turn pitch is the pitch per 360° of the helix (one revolution). Consequently, a turn is understood to be a 360° section of the helix, and the turn pitch is understood to be the length or distance from the beginning of one turn to the beginning of the immediately adjacent turn in the conveying direction. The turn pitch or the pitch of the helix can thus be understood analogously to the pitch of a spiral spring.

[0014] In developing the invention, it was recognized that overload events due to the feed material becoming trapped between the screw shafts occur when the feed material becomes trapped in a screen gap between two screw shafts. The screen gaps occur between two directly adjacent screw shafts, between the directly adjacent spirals, when the spirals of the screw shafts mesh. The separation grain or fine grain fraction is separated via the screen gaps. A screen gap has an opening that is at least parallelogram-shaped.

[0015] It has also been recognized that overload events and jamming of the feed material in a screen gap usually occur when the screen gap decreases in the conveying direction. Such a reduction can result from a decrease in the pitch of the screw shaft in the conveying direction, which is due to manufacturing reasons. In practice, it is common practice to weld the helix, especially the previously rolled one, to the core tube. Welding solutions generally exhibit a higher degree of precision deviation than components manufactured by machine, preferably by turning and / or milling.

[0016] As tests have shown, feed material often becomes trapped in the screen gap due to a reduction in the screen gap in the conveying direction, especially in applications with a high proportion of very hard, cubic feed material in the limit range of the separation grain size that is separated via the screen gap.

[0017] According to the invention, a technical solution can therefore be provided that highly likely reduces the frequency of such local overload events. Advantageously, the screen gap, in particular the width of the screen gap, increases in the conveying direction, so that jammed feed material, in particular cubic feed material, can be separated as a fine-grain fraction below the screw shaft deck. Consequently, the constraint and the previously described, marginal and critical dimension of the screen gap can be avoided. Consequently, it is also possible to reliably prevent manufacturing tolerance-related changes in pitch or length between immediately consecutive winding spacings from leading to a local reduction in the width of the screen gap.

[0018] The operating conditions of the separation device are ultimately significantly improved by the invention, since overload events, particularly due to preferably cubic feed material trapped in the screen gap, can be reduced by up to 80%. This increases the service life of the entire separation device and also reduces operating costs when using the separation device according to the invention, since costly repairs following machine failure due to an overload event can be significantly reduced, preferably by more than 70%.

[0019] Furthermore, according to the invention, the noise level during operation of the device can be significantly reduced, preferably by at least 30%. Furthermore, overload events accompanied by shrill noises and loud grinding can be reliably prevented.

[0020] By increasing the pitch of the screw shaft's threads in the conveying direction, the feed material is pulled apart in the axial direction of the screw conveyors—that is, in the conveying direction. The pitch of the threads at the free end and / or discharge end of the screw shaft is therefore preferably greater than at the bearing end or feed end. The pitch of the threads preferably increases toward the free end and / or discharge end. The conveying direction extends from the feed end to the discharge end.

[0021] The spreading of the feed material results in a reduction in the layer height of the feed material toward the discharge end, thus improving the separation effect. By increasing the pitch of the screw shaft in the conveying direction, at least in some areas, the separation result can be achieved by better separating entangled feed material.

[0022] In the embodiment according to the invention, it is provided that the spirals of immediately adjacent screw shafts intermesh. It is preferably provided that the spiral runs spirally around the core tube. If the spirals of the screw shafts intermesh, a self-cleaning process can be achieved, whereby a virtually wrap-free system or a wrap-free device is provided. This means that it can be reliably prevented that feed material wraps around the outside of the screw shafts or "winds up" on them. The outer edge of the spiral of an immediately adjacent screw shaft engages in the free space between two turns of the spiral of the immediately adjacent screw shaft. Accordingly, meshing of immediately adjacent screw shafts is provided.

[0023] The intermeshing of the screws creates a preferably parallelogram-shaped opening between the directly opposite helices of the screw shafts, which is also referred to as the screen gap. This screen gap defines the particle size that is separated below the deck. This clear dimension therefore characterizes the rotation angle offset between two adjacent screw shafts. The intermeshing of the screw shafts allows highly branched or adhering feed material to be separated from one another and divided into different fractions. Likewise, the exposed surface of the core tube can be freed of feed material adhering to the core tube, particularly material containing clay.

[0024] Furthermore, in a further preferred embodiment, at least two directly adjacent screw shafts, in particular all screw shafts, have the same direction of rotation. The identical direction of rotation of the screw shafts ultimately results in a further conveying direction orthogonal to the axis of rotation. In particular, elongated feed material can be separated in the direction of the further conveying direction.

[0025] According to the invention, the device is designed such that separation into at least three fractions takes place, with separation into at least two fractions taking place above the screw shafts. The separation of the first feed material can take place in the conveying direction parallel to the axis of rotation. In this conveying direction, in particular cubic, non-elongated feed material is separated. A further fraction can take place below the spiral shaft deck or below the spiral shafts, with the separation grain size resulting from the screen gap between immediately adjacent screw shafts. Finally, a third fraction can be separated in the direction of the further conveying direction orthogonal to the axes of rotation, with the third fraction comprising elongated, non-cubic feed material which preferably has a length greater than one winding pitch, more preferably greater than two winding pitches.

[0026] Ultimately, however, it can also be provided that the worm shafts, especially those at the ends, have a different direction of rotation in some sections

[0027] It is particularly preferred that the pitch of all screw shafts increases at least in some areas in the conveying direction. According to the invention, the pitch of all screw shafts increases in the conveying direction, meaning that the length of at least two immediately consecutive pitches of a screw shaft increases in the conveying direction. The advantage of increasing the pitch of all screw shafts in the conveying direction is that, with intermeshing screw shafts, the screen gap increases at least in some areas in the conveying direction. This allows feed material trapped in a screen gap to be separated in the conveying direction via transport along the screw shaft.

[0028] Furthermore, according to a preferred embodiment of the inventive concept, the winding spacing increases monotonically, preferably strictly monotonically, in the conveying direction. A monotonous increase in the winding spacing is understood according to the invention to mean that the winding spacing increases in the conveying direction or remains at a constant level. If n indicates the number of windings and a n the length of the winding pitch after n turns, this means: an−1≤an

[0029] The number of turns n increases in the conveying direction.

[0030] According to the invention, a strictly monotonic increase in the winding spacing means that all winding spacings increase in the conveying direction: an−1 <an

[0031] A monotonic increase in the coil spacing in the conveying direction therefore requires that immediately adjacent coil spacings in the conveying direction either increase or stagnate at a constant value. Thus, according to the invention, it is ultimately possible for the screw shaft to have a constant coil spacing / pitch up to half of its effective length, particularly starting from the clamping point, and for the coil spacing to increase monotonically, preferably strictly monotonically, particularly nonlinearly and / or disproportionately, preferably exponentially, in the second half.

[0032] Consequently, a strictly monotonic increase in the pitch of the coils in the conveying direction requires that all immediately adjacent pitches increase in the conveying direction, so that the pitch of the coils in the conveying direction increases, in particular, steadily or continuously. The advantage of such an increase in the pitch of the coils is that it can prevent a reduction in the length and / or size of the screen gap after the screen gap has widened. A monotonic, preferably strictly monotonic, increase or increase in the pitch of the coils can ensure that the screen gap of immediately adjacent screw shafts increases or increases monotonically, preferably strictly monotonically, in the conveying direction.

[0033] Furthermore, the percentage increase in the coil pitch in the conveying direction is preferably at least substantially the same between two immediately adjacent coil pitches. Consequently, between two immediately adjacent coil pitches, the subsequent coil pitch seen in the conveying direction is always at least substantially greater by the same percentage increase factor. To calculate the length of the coil pitches after n turns, an analogy to compound interest can be assumed. Thus, the pitch after n turns is calculated by the distance or length of the first coil pitch a0 and the percentage increase in the pitch or coil pitch p in the conveying direction: an=ao(1+p100)n n = number of turns a0 = length of first winding pitch a n = Length of the winding pitch after n turns p = percentage increase

[0034] Ultimately, however, it is understood that in practice, deviations from the theoretical calculation of the increase in the coil pitch due to manufacturing tolerances exist. In particular, the deviation from the calculated length of the coil pitch due to manufacturing tolerances is + / - 20% for up to ten coils.

[0035] Furthermore, according to a preferred embodiment, the percentage increase in the coil spacing in the conveying direction is greater than 1%, preferably greater than or equal to 2%, preferably between 2% and 20%, more preferably between 4% and 10%, most preferably between 4% and 6%. In practice, it has been found that, due to the welding technology used to manufacture the screw shafts, tolerances in the pitch or coil spacing of the helix of a maximum of 2% per coil spacing or per 360° (per revolution) of the helix, in particular of a maximum of 1% per coil spacing or per 360° (per revolution) of the helix, exist.According to the invention, the percentage increase between two immediately adjacent pitches in the conveying direction exceeds the possible manufacturing tolerance of the pitch resulting from the production of the screw shaft, so that it can be reliably guaranteed that even with a welded production of the screw shaft, the pitch in the conveying direction can increase at least in some areas. Consequently, the screen gap in the conveying direction can also increase at least in some areas.

[0036] Preferably, the pitch or the pitch of the turns as a whole - in comparison from the smallest to the largest pitch, i.e. from the shaft start or feed end to the shaft end or discharge end - increases by up to 70%, preferably between 30% and 60%, more preferably between 40% and 50%.

[0037] In a further preferred embodiment of the inventive concept, it is provided that the smallest distance between immediately adjacent helices of immediately adjacent screw shafts increases in the conveying direction. Preferably, the smallest distance increases monotonically, more preferably strictly monotonically, in the conveying direction. Immediately adjacent helices enclose two distances with each other, namely the smallest distance between the helices and the separation particle size distance, which indicates the width of the larger screen gap. Consequently, the separation particle size distance of immediately adjacent helices and immediately adjacent screw shafts preferably also increases in the conveying direction, in particular wherein the separation particle size distance increases monotonically, preferably strictly monotonically, in the conveying direction. The separation particle size distance thus defines the distance between adjacent turns of adjacent helices

[0038] Preferably, the spacing between adjacent coils is adjustable. This ensures the separation of difficult-to-separate materials with the ability to adjust the screen gap.

[0039] The screw shafts are arranged in such a way that they form a screen deck, which is usually used for classifying solid and lumpy application or feed material. The screen deck can have a screen length - transverse to the conveying direction - of 2 to 10 m, preferably 4 to 6 m. The screen width or the length of the screw shaft in the conveying direction is between 0.5 to 5 m, preferably between 1 to 4 m, more preferably between 2 to 3 m. The device is intended for the separation of feed material from the recycling sector and for waste material, commercial waste and construction rubble. The aforementioned different feed materials have in common that they do not have evenly distributed structures and geometries, whereby feed material pieces may become entangled with one another.

[0040] Especially when used in the waste and recycling sectors, adjusting the screen deck or screen size is advantageous for clean and selective classification of the feed material. This adjustment is done in such a way that the smallest distance between the outer edge of the screw shaft and the immediately adjacent outer edge of the screw shaft is changed in the axial direction. Ultimately, to change the screen deck, the screw shafts are rotated relative to each other, so that the clearance between two immediately adjacent core tubes also changes, becoming either larger or smaller.

[0041] In practice, various screen deck configurations have proven advantageous. For example, a very small minimum pitch and consequently a large pitch between adjacent turns or a large particle size separation between two immediately adjacent spirals is suitable for providing a large clearance or a large screen gap between two immediately adjacent core tubes. Accordingly, this arrangement enables a very large passage width, so that this arrangement is usually used for the separation of elongated feed material or long parts.

[0042] By rotating or adjusting adjacent spiral shafts, each arranged continuously in the working direction or in the direction of the further conveying direction, the minimum distance or the clear distance in the axial direction can be variably adjusted and even set to a maximum value, so that the clearance between immediately adjacent screw shafts is kept to a minimum. This position can be used, for example, for separating less elongated material or bottles.

[0043] In the aforementioned settings, it is advantageous if all screw shafts have the aforementioned position relative to one another or if all screw shafts are arranged at least substantially equivalently or in the same way relative to one another.

[0044] Adjusting the screen deck or changing the position of the screw shafts, especially when rotating the screw shafts, is also referred to as adjusting the angle offset. Changing the position of the screw shafts from one to the next, relative to each other, allows the classification behavior to be influenced in the same way.

[0045] By rotating the screw shafts relative to each other and / or by changing the offset of two adjacent screw shafts, material with an at least substantially cubic and / or an at least substantially non-elongated shape can be screened, particularly approximately, as the separation grain and / or sieve passage. Feed material pieces with a length exceeding 2.5 to 4 spiral pitches or spiral pitches remain, in particular, above the screen deck. If a feed material piece has a length in the limit range of 1.5 to 3 spiral pitches or pitch units, the separation cannot occur deterministically but rather randomly.

[0046] The smallest pitch between the screws influences not only the passage width and the particle size, but also the fraction and / or fractions that are separated transversely or in the direction of the rotation axis. Rotating the screw shafts relative to each other can achieve different process results or classification results. Depending on the feed material, the classification result and the fraction to be removed can be flexibly adjusted.

[0047] According to the inventive embodiment of the inventive concept, as previously mentioned, the spirals of immediately adjacent screw shafts engage with one another, wherein more preferably the radial distance from the outer spiral edge to the core tube immediately adjacent to the outer spiral edge is greater than 1 mm. In particular, the distance lies in a range between 2 and 3 mm. Accordingly, the distance between immediately adjacent core tubes is determined by the web height of the spirals and the distance from the outer spiral edge to the core tube, i.e. ultimately the web height plus a few millimeters. Preferably, all screw shafts have at least substantially the same web height. Particularly preferably, the screw shafts are at least substantially structurally identical.

[0048] In addition, a drive device can be provided that drives the screw shafts at a synchronous angular velocity. Consequently, the screw shafts preferably all rotate in the same direction and are also driven at the same angular velocity, whereby the distance between adjacent turns does not change during the operating state of the device.

[0049] The drive device can have a plurality of connecting means, in particular geared roller chains, each of which interacts with a drive means of the worm shaft. At least one gear, for example, can be provided as the drive means. Preferably, the motor of the drive device is arranged on only one worm shaft. The other worm shafts are connected to this worm shaft via the connecting means, with one connecting means connecting two directly adjacent worm shafts to each other, so that two connecting means are arranged on each worm shaft—except for the edge-side worm shafts.

[0050] In this context, a further advantage of the invention becomes apparent. Until now, if a feed material becomes wedged in the middle of the screen deck between two screw shafts and can no longer be conveyed away in the conveying direction, the screw shafts connected to one another by the jammed feed material can no longer rotate. Consequently, all subsequent screw shafts in the direction of further conveying that are connected to the stationary screw shafts can no longer rotate. However, all screw shafts are indirectly connected to the motor of the drive device. Consequently, at least part of the screen deck comes to a standstill, and a tearing of the connecting means - and therefore of the geared roller chains - cannot generally be prevented, which can result in serious damage to the drive device. According to the invention, this problem can be avoided by increasing the winding spacing in the conveying direction.

[0051] Particularly preferably, the core tube is at least substantially cylindrical in shape, in particular wherein the core tube has a constant outer diameter in the conveying direction.

[0052] Preferably, the axes of rotation of the screw shafts are arranged parallel to each other and / or run parallel to each other, whereby the separation result can be optimized, since the feed material can be conveyed over the screen deck in the conveying direction and in the direction of the further conveying direction, i.e. transversely to the axis of rotation.

[0053] The screw shafts can be arranged to form a flat or curved screen deck. In particular, the screw shafts are arranged in a horizontal or inclined plane, or are curved, preferably trough-shaped. Furthermore, the screw shafts can be mounted on one or both sides in a holder. The choice between a flat or curved screen deck can depend on the intended use and the feed material. A curved screen deck is particularly suitable when the feed material is to remain above the screen deck for a longer period of time. A combination of a flat and a curved screen deck can also be adapted to the process conditions, depending on the application.

[0054] The use of a one-sided or two-sided mount depends on the intended use of the separation device. With a one-sided mount, it is advantageous that separation can take place into at least two fractions: one fraction below the screen deck, one fraction in the direction of the further conveying direction, i.e. transverse to the axes of rotation, and one fraction in the conveying direction, i.e. at least essentially parallel to a respective axis of rotation. Bearing on both sides can create a high level of stability for the screen deck, enable the classification of feed material with a very high dead weight, and be safely designed to withstand overload or excessive strain, thus reliably preventing machine breakage. Even with bearings on both sides, separation into three fractions can take place, whereby the fraction can be discharged in the conveying direction, i.e. in the direction of the axis of rotation, over the bearing.

[0055] In particular, the support with the screw shafts and / or the screen deck is designed to be tiltable in at least one direction, preferably in all directions. The height of the support can be adjustable. Accordingly, the entire screen deck with the screw shafts can be tilted depending on the respective application, in particular the feed material to be classified.

[0056] Further advantages and possible applications of the present invention will become apparent from the following description of embodiments with reference to the drawings and the drawing itself.

[0057] It shows: Fig. 1 a schematic plan view of a device according to the invention for separating feed material, Fig. 2 a schematic perspective view of a further embodiment of a separating device according to the invention, Fig. 3 a schematic perspective view of a further embodiment of a separating device according to the invention, Fig. 4 a schematic perspective view of a worm shaft according to the invention, Fig. 5 a schematic perspective view of the Fig. 4 shown worm shaft according to the invention and Fig. 6 a schematic side view of the Fig. 4 and Fig. 5 shown worm shaft according to the invention.

[0058] The Fig. 1 shows a device 1 for separating feed material 2 with at least two screw shafts 3. In the Fig. 1, six screw shafts 3 are shown. The screw shaft 3 has a core tube 4 and a helix 5 with a plurality of turns 6. In the embodiments shown, the helix 5 runs spirally around the core tube 4. One turn 6 characterizes one revolution / rotation of the helix 5 by 360°. Adjacent turns 6 are spaced from one another by the turn spacing 7. The turn spacing 7 is the so-called pitch of the helix 5. The conveying direction X of the screw shaft 3 runs at least substantially parallel to the axis of rotation 8 of the screw shaft 3. The conveying direction X extends from the feed end 17 - i.e. the supported end - to the discharge end 16 of the screw shaft 3. The discharge end 16 is shown as the free end of the screw shaft 3. In other embodiments not shown, the discharge end 16 can also be supported by a bearing.

[0059] The Fig. 1, that the winding spacing 7 in the conveying direction X of at least one screw shaft 3 increases at least in some areas. In the illustrated embodiments, it is shown that the winding spacing 7 increases not only in some areas, but over the entire longitudinal extent of the screw shaft 3. What is not shown is that the winding spacing 7 only increases in sections or in some areas over at least two adjacent winding spacings 7 in the conveying direction X. For example, starting from the clamping point or the beginning of the screw shaft 3, thus the feed end 17, the winding spacing 7 can only increase from half the length of the screw shaft 3 in the conveying direction X.

[0060] The conveying direction X results for each screw shaft 3 and follows from the rotational movement of the screw shaft 3 - consequently from the rotation of the helix 5.

[0061] The Fig. 2 shows that the feed material 2 is fed via a feeding device 14 by means of a feeding means 15, in the illustrated embodiment a conveyor belt, onto the screen deck formed by the screw shafts 3. Cubic and / or non-elongated materials are separated in the direction of conveying direction X—i.e., above the screen deck. The separation grain or the fine grain fraction, i.e., the smaller components, falls between the free spaces created between two immediately adjacent screw shafts 3 and thus below the screen deck. A third fraction can be separated transversely to the conveying direction X in the direction of the further conveying direction Y, wherein this fraction can comprise elongated feed material 2. The further conveying direction Y extends orthogonally or transversely to the conveying direction X.

[0062] In the Fig. 1 to Fig. 3 shows that the helices 5 of immediately adjacent screw shafts 3 interlock, resulting in meshing of the screw shafts 3. This results in the so-called self-cleaning effect of the screw shafts 3, since the surface can be kept free of feed material 2 adhering to it, for example, feed material 2 containing clay. Furthermore, wrapping of the feed material 2 around the screw shaft 3 can be reliably prevented.

[0063] Furthermore, in the illustrated embodiments, at least two directly adjacent screw shafts 3 have the same direction of rotation. According to the illustrated embodiment, all screw shafts 3 have the same direction of rotation. The identical direction of rotation of all screw shafts 3 enables the further conveying direction Y transverse to the conveying direction X and thus transverse to the axes of rotation 8.

[0064] The Fig. 1 shows that the pitch 7 of all screw shafts 3 in the conveying direction X increases at least in some areas. Fig. 1, the pitch 7 of all screw shafts 3 in the conveying direction X increases not only in sections, but over the entire longitudinal extent of the screw shafts 3.

[0065] The Fig. 4 to Fig. 6 show that the winding distances 7 increase monotonically in the conveying direction X. According to the Fig. In the embodiment shown in Figure 6, the winding spacings 7 increase strictly monotonically in the conveying direction X. A strictly monotonous increase in the winding spacings 7 means that the subsequent winding spacing 7 in the conveying direction X is always greater than the previous winding spacing 7 seen in the conveying direction X. Consequently, the ratio of the winding spacings 7 is as follows: a0 <a1<a2<a3<a4<a5<a6<a7

[0066] The coil spacing a0 is the smallest coil spacing 7, which increases strictly monotonically in the conveying direction X, up to the coil spacing a7.

[0067] In an embodiment not shown, the coil spacings 7 increase monotonically, but not strictly monotonically, in the conveying direction X. For example, the coil spacings a0 to a4 can be the same or identical and only increase strictly monotonically from coil spacing a5 to coil spacing a7. This results in: a0=a1=a2=a3=a4 and a4 <a5<a6<a7

[0068] Alternatively, according to another embodiment, it is also possible: a0=a and a1 <a2<a3<a4 and a4=a5=a6 and a6 <a7

[0069] Furthermore, the Fig. 6, it is provided that the percentage increase p of the winding pitch 7 in the conveying direction X is at least substantially the same between two immediately adjacent winding pitches 7. This means that the increase p between two winding pitches 7, for example between a1 and a2, is just as large as the increase p of the winding pitch 7 between a4 and a5. The winding pitch 7 a n can therefore be calculated after n turns 6 - in analogy to the increase of compound interest - as follows: an=ao(1+p100)n

[0070] However, due to manufacturing tolerances, the above calculation may deviate by up to + / - 20% for up to ten turns 6.

[0071] The percentage increase of the coil pitch 7 in the conveying direction is greater than 1%. In the above formula, the percentage increase would be p. In addition, the Fig. 4 to Fig. 6 shows an increase in the pitch 7 between 2 and 20%. Fig. 6, the percentage increase in the winding pitch 7 is approximately 6% + / - 1%.

[0072] Fig. Figure 1 shows that two immediately adjacent screw shafts 3 and the immediately adjacent spirals 5 define two distances, and consequently two screen gaps. The aforementioned distances are the smallest distance 9 between immediately adjacent spirals 5 of immediately adjacent screw shafts 3 and the distance 10 between adjacent turns 6. The distance 10 characterizes the separation grain size and can also be referred to as the separation grain size distance. The distance 10, or the separation grain size distance, defines the parallelogram-shaped screen gap. A further screen gap is, of course, defined by the smallest distance 9.

[0073] The smallest distance 9 and the distance 10 between adjacent turns 6 of immediately adjacent spirals 5 of immediately adjacent screw shafts 3 increases in the conveying direction X. In the Fig. 1 to Fig. In the embodiment shown in Figure 3, the smallest distance 9 and the distance 10 increase strictly monotonically in the conveying direction X.

[0074] Not shown is that the distance 10—and consequently also the smallest distance 9—between adjacent turns 6 of adjacent spirals 5 is adjustable. Accordingly, the so-called angle offset between directly adjacent screw shafts 3 and consequently also the respective screen gap are adjustable.

[0075] In Fig. 1 shows a drive device 11 that drives the screw shafts 3 at a synchronous angular velocity. The drive device 11 is arranged on an end-side screw shaft 3 facing the feeding device 14. The screw shafts 3 are connected to one another via connecting means (not shown), in particular geared roller chains, which each act between two immediately adjacent screw shafts 3.

[0076] The connecting means (not shown) are arranged on the drive means 18 and interact with them. In the illustrated embodiments, the drive means 18 are designed as sprockets or gears and are arranged on the worm shaft 3 itself. The torque is transmitted to the core tube 4 via the connecting means and the drive means 18. Two drive means 18 are provided on each of the worm shafts 3, since two connecting means are arranged on the worm shafts 3—except for the edge-side worm shafts 3.

[0077] The helices 5 of all worm shafts 3 have at least substantially the same web height 12. Furthermore, the worm shafts 3 are at least substantially identical in construction and are merely rotated relative to one another for arrangement in the holder 13.

[0078] The worm shaft 3 has a cylindrical core tube 4, as can be seen from the Fig. 4 to Fig. 6 results.

[0079] According to the Fig. 1 to Fig. 3, the axes of rotation 8 of the screw shafts 3 run parallel to one another. Furthermore, the screw shafts 3 are arranged in a horizontal plane. Not shown is that the axes of rotation 8 of the screw shafts 3 can also not run parallel to one another and / or that the screw shafts 3 are arranged in an inclined plane or curved, preferably trough-shaped. With a trough-shaped arrangement of the screw shafts 3, the conveying direction X results for each screw shaft 3. A plurality of conveying directions X is therefore provided. The winding pitch 7 would therefore increase at least in some regions in the conveying direction X of the respective screw shaft 3 - at least one screw shaft 3.

[0080] In the illustrated embodiments, the screw shafts 3 are mounted on one side in a holder 13. Not shown is that the screw shafts 3 can also be mounted on both sides in a holder 13, whereby a fraction can also be discharged via the holder 13.

[0081] Furthermore, it is not shown that the holder 13 with the worm shafts 3 is designed to be tiltable in at least one direction, in particular in all directions. Likewise, it is not shown that the height of the holder 13 is adjustable. List of reference symbols 1 device 2 Feed material 3 Worm shaft 4 core tube 5 spirals 6 turns 7 winding spacing 8 axis of rotation 9 smallest distance 10 distance 11 Drive device 12 bridge height 13 Bracket 14 Feeding device 15 Feed materials 16 shedding ends 17 End of task 18 Propulsion means X Conveying direction Y further conveying direction a0-a7 winding spacing

Claims

[1] Use of a device (1) for separating different solid fractions of a solid mixture as feed material (2) in a mechanical separation process with at least two screw shafts (3), wherein the screw shaft (3) has a core tube (4) and a helix (5) running, in particular spirally around the core tube (4), with a plurality of turns (6), wherein adjacent turns (6) are spaced from one another by a turn distance (7), wherein the conveying direction (X) of the screw shaft (3) runs at least substantially parallel to the axis of rotation (8) of the screw shaft (3), wherein the screw shafts (3) are arranged such that they form a screen deck which is used for classifying solid and lumpy feed material (2), wherein the helices (5) of immediately adjacent screw shafts (3) engage with one another, wherein the device (1) is designed such thatthat a separation into at least three fractions takes place and that a separation into at least two fractions takes place above the screw shafts (3), , characterized by that the winding spacing (7) of at least one screw shaft (3) increases at least in some areas in the conveying direction (X). [2] Use according to claim 1, characterized by that at least two immediately adjacent worm shafts (3), in particular all worm shafts (3), have the same direction of rotation. [3] Use according to one of the preceding claims, characterized by that the pitch (7) of all screw shafts (3) in the conveying direction (X) increases at least in some areas. [4] Use according to one of the preceding claims, characterized by that the winding spacings (7) increase monotonically, preferably strictly monotonically, in the conveying direction (X). [5] Use according to one of the preceding claims, characterized bythat the percentage increase of the winding spacing (7) in the conveying direction (X) is at least substantially the same between two immediately adjacent winding spacings (7). [6] Use according to one of the preceding claims, characterized by that the percentage increase of the winding spacing (7) in the conveying direction (X) is greater than 1%, preferably greater than or equal to 2%, preferably between 2% and 20%, more preferably between 4% and 10%, most preferably between 4% and 6%. [7] Use according to one of the preceding claims, characterized by that the smallest distance (9) and / or the distance (10) between adjacent turns (6) of immediately adjacent spirals (5) of immediately adjacent screw shafts (3) increases in the conveying direction (X), in particular wherein the smallest distance (9) and / or the distance (10) increases monotonically, preferably strictly monotonically, in the conveying direction (X). [8] Use according to any one of the preceding claims, characterized by that the distance (10) between adjacent turns (6) of adjacent spirals (5) is adjustable and / or that a drive device (11) is provided which drives the worm shafts (3) at a synchronous angular velocity. [9] Use according to one of the preceding claims, characterized by that the helices (5) of all worm shafts (3) have at least substantially the same web height (12) and / or that the worm shafts (3) are at least substantially structurally identical.

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